The present invention relates to a method for polymerizing alpha-olefins, a catalyst for such a polymerization and a method for producing such a catalyst. A particular aspect of the present invention relates to a method for producing linear low density polyethylene.
Linear low density polyethylene polymers possess properties which distinguish them from other polyethylene polymers such as homopolymers of polyethylene. Certain of these properties are described in the Anderson et al U.S. Pat. No. 4,076,698.
The Karol et al U.S. Pat. No. 4,302,566 describes a process for producing certain linear low density polyethylene polymers in a gas phase, fluid bed reactor.
The Graff U.S. Pat. No. 4,173,547, Stevens et al U.S. Pat. No. 3,787,384, Strobel et al U.S. Pat. No. 4,148,754 and the Ziegler, deceased et al U.S. Pat. No. 4,063,009 each describe various polymerization processes suitable for producing forms of polyethylene other than linear low density polyethylene, per se.
The Graff U.S. Pat. No. 4,173,547 describes a supported catalyst obtained by treating a support with both an organoaluminum compound and an organomagnesium compound followed by contacting this treated support with a tetravalent titanium compound.
The Stevens et al U.S. Pat. No. 3,787,384 and the Strobel et al U.S. Pat. No. 4,148,754 describe a catalyst prepared by first reacting a support (e.g., silica containing reactive hydroxy groups) with an organomagnesium compound (e.g., a Grignard reagent) and then combining this reacted support with a tetravalent titanium compound. According to the teachings of both of these patents, no unreacted organomagnesium compound would seem to be present when the reacted support is contacted with the tetravalent titanium compound.
The Ziegler, deceased et al U.S. Pat. No. 4,063,009 describes a catalyst which is the reaction product of an organomagnesium compound (e.g., an alkylmagnesium halide) with a tetravalent titanium compound. This reaction with the tetravalent titanium compound takes place in the absence of a support material.